THIS invention relates to apparatus for monitoring the manner in which a vehicle is driven. The apparatus may be used to record instances of poor driving or to provide an indication to the driver of a vehicle or some other person that the vehicle is being badly driven.
Devices of this type which provide warning or recording signals when a vehicle is subjected to excessive acceleration during cornering, or when a vehicle is driven at speed over a badly potholed road or rough surface, are known. Generally such devices include switches which consist of tubes which contain mercury and which are installed in the vehicle at an incline so that accelerative forces on the switch cause a globule of mercury to travel up the inclined tube or capsule and if the accelerative force is sufficiently high electrically to connect a pair of contacts at the upper end of the tube.
To prevent spurious operation of the switch caused for example by splashing of the mercury the capsules have been made relatively long so that the contacts at the upper end of the capsule are well spaced from the mercury at the lower end of the capsule. This solution however carries with it its own disadvantages for the mercury must travel a fairly long distance inside the tube before the contacts are closed and the travel time may vary from switch to switch because of different surface tension effects, capsule sizes and capsule linearities.